This application is a continuation-in-part of my copending application Ser. No. 744,613, filed Oct. 10, 1991.
1. Field of the Invention
This invention is directed to particle sortation in an isokinetic separator apparatus where oversize particles are selectively isolated from an air stream and returned in bypass of the apparatus for further reduction to micronized fineness.
2. Description of the Prior Art
In the processing of particulate material, like coal, rock and similar particulates that require reduction in size of the particles, apparatus has been created of the character shown in U.S. Pat. No. 4,993,647 of Feb. 19, 1991; U.S. Pat. No. 4,830,290 of May 16, 1991; U.S. Pat. No. 4,778,061 of Oct. 18, 1988; U.S. Pat. No. 4,641,788 of Feb. 10, 1987; U.S. Pat. No. 4,602,744 of Jul. 29, 1986; U.S. Pat. No. 4,566,639 of Jan. 28, 1986; and U.S. Pat. No. 4,522,343 of Jun. 11, 1985. Each of the apparatus disclosed in the foregoing prior art embodies either an impact hammer mill or a roller grinding mill in combination with an outlet connect into a motor driven separator of centrifugal or spinner classifying character.
The problem with the prior art is that the centrifugal separator device in the apparatus requires some form of motor drive which increases the horsepower consumption. In addition, the apparatus usually operates to classify the particulates in the grinding mill outlet for the purpose of separating the large particles, or those not sufficiently ground or reduced from a desired acceptable smaller micron particle size. Such apparatus has forced large particles to fall in counterflow to the incoming material, which counterflow interferes with and actually reduces the capacity of the apparatus while increasing the horsepower consumption to meet a desired output.